Nb-20%Ta alloy powder by the hydriding-dehydriding technique

Nb-Ta alloys have been used in the chemical industry to substitute pure Ta in corrosive environments (inorganic acids at high temperature). The production of components from these alloys does not show important technical problems due to the high ductility of these materials. The present work is aimed at the production of Nb-20%Ta (wt%) alloy powders by the hydriding-dehydriding technique. The alloy was produced in ingot form by the aluminothermic reduction of oxides (Nb2O5/Ta2O5) and electron beam melting. The hydriding step has been carried out in a hydrogen gas atmosphere at different temperatures using chips machined from the ingot. No significant hydriding has been observed in the experiments carried out below 500 degrees C, meaning that it is the lowest possible hydriding temperature of the material through the adopted experimental procedure. The XRD patterns of the hydride and Nb-20%Ta powders coincide with those of beta-NbH0.89 and Nb XRD standards, respectively. The powders were of angular and irregular morphology. The specific masses of the hydride and Nb-20%Ta powder were determined as approximately 8.55 and 9.57 g/cm(3), respectively. The apparent and TAP specific masses of the hydride and Nb-20%Ta powders were (4.30/5.60) and (4.65/6.10) g/cm(3), respectively. (C) 2005 Elsevier Ltd. All rights reserved.